This invention relates generally to roof ventilators, and particularly to an air deflector for impeding the flow of wind or blowing air through the multiplicity of air passages from the exterior of the roof ventilator and diverting the flow of blowing air over the top panel of the roof ventilator.
Embodiments of a foldable corrugated plastic ridge cap roof ventilator have previously been disclosed in U.S. Pat. Nos. 4,803,813 to Fiterman and 5,094,041 to Kasner, the content of those patents (including the related applications, documents, and references) being incorporated herein by reference as though fully set forth. The details and description of the fabrication, assembly, and use of the roof ventilators shown in the Fiterman '813 and Kasner '041 patents should be assumed to apply in all pertinent respects to the roof ventilator discussed herein, with the exception of the particular variations and modifications set forth and described with particularity. The improvement disclosed herein is equally applicable to and may be incorporated into many other types of ridge cap type roof ventilators.
Because the exposed outer edges of the vent parts are raised above the normal plane of the shingles or other roofing material and present a blunt edge or surface, and the roof ventilator is further covered with shingles or roofing materials that may overhang the outer edges of the vent parts, it is important to protect the roof ventilator and roofing materials from high winds that can carry particulate matter and foreign objects from the exterior of the roof ventilator through the multiplicity of air passages into the interior of the roof ventilator, interfere with the normal venting process by preventing convective forces from drawing air out through the air passages, and which may lift or tear the roof ventilator and surrounding roofing materials from the roof and thereby cause extensive damage.
There is currently a difference of opinions among those in the field of installing such roof ventilators regarding the optimum distance that an air flow blocking member should be spaced apart from the outer edge of the corresponding vent part. The range of preferred distances includes mounting the air flow blocking member closely proximate to or in contact with the outer surface of the vent part, or away from the outer edge of the vent part by up a to few inches.
U.S. Pat. No. 4,843,953 to Sells discloses a roof ventilator having a flashing strip which is an inverted V-shaped or acutely-angled perforated metal cover for the outer edges of the vent parts. One leg of the flashing strip is inserted between the top panel and the vent part, with the other leg depending substantially flush with the outer edge of the vent part in covering relation to the air passages. The Sells '953 device is intended to mitigate against the introduction of foreign objects and insects into the air passages, and may retard or reduce the volume or rate of air flowing from the exterior of the roof ventilator through the air passages, but will not protect the roof ventilator or roofing material from being lifted or torn by high winds.
Air Vent, Inc. of Peoria Heights, Illinois manufactures a roof ventilator having a unitary air flow guard with a base member that is inserted between the stacked panels of the vent part and are fixedly attached to the vent part. An air flow blocking member extends from the base member at a right angle and is spaced a predetermined fixed distance from the outer edge of the vent part. That distance is normally on the order of 1/2"-3/4", but the unitary roof vent and air flow guard may also be fabricated so that the air flow guard is fixed substantially flush with the outer edge of the vent part or alternately spaced a greater distance away. The air flow guard impedes the direct flow of wind blowing through the air passages from the exterior of the roof ventilator and diverts a portion of the air flow across the top of the roof ventilator.